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Linux kernel mirror (for testing) git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
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#define STACK_CREATE_FLAG_MASK \ (BPF_F_NUMA_NODE | BPF_F_RDONLY | BPF_F_WRONLY | \ BPF_F_STACK_BUILD_ID)
struct stack_map_bucket { struct pcpu_freelist_node fnode; u32 hash; u32 nr; u64 data[];};
struct bpf_stack_map { struct bpf_map map; void *elems; struct pcpu_freelist freelist; u32 n_buckets; struct stack_map_bucket *buckets[] __counted_by(n_buckets);};
static inline bool stack_map_use_build_id(struct bpf_map *map){ return (map->map_flags & BPF_F_STACK_BUILD_ID);}
static inline int stack_map_data_size(struct bpf_map *map){ return stack_map_use_build_id(map) ? sizeof(struct bpf_stack_build_id) : sizeof(u64);}
/** * stack_map_calculate_max_depth - Calculate maximum allowed stack trace depth * @size: Size of the buffer/map value in bytes * @elem_size: Size of each stack trace element * @flags: BPF stack trace flags (BPF_F_USER_STACK, BPF_F_USER_BUILD_ID, ...) * * Return: Maximum number of stack trace entries that can be safely stored */static u32 stack_map_calculate_max_depth(u32 size, u32 elem_size, u64 flags){ u32 skip = flags & BPF_F_SKIP_FIELD_MASK; u32 max_depth; u32 curr_sysctl_max_stack = READ_ONCE(sysctl_perf_event_max_stack);
max_depth = size / elem_size; max_depth += skip; if (max_depth > curr_sysctl_max_stack) return curr_sysctl_max_stack;
return max_depth;}
static int prealloc_elems_and_freelist(struct bpf_stack_map *smap){ u64 elem_size = sizeof(struct stack_map_bucket) + (u64)smap->map.value_size; int err;
smap->elems = bpf_map_area_alloc(elem_size * smap->map.max_entries, smap->map.numa_node); if (!smap->elems) return -ENOMEM;
err = pcpu_freelist_init(&smap->freelist); if (err) goto free_elems;
pcpu_freelist_populate(&smap->freelist, smap->elems, elem_size, smap->map.max_entries); return 0;
free_elems: bpf_map_area_free(smap->elems); return err;}
/* Called from syscall */static struct bpf_map *stack_map_alloc(union bpf_attr *attr){ u32 value_size = attr->value_size; struct bpf_stack_map *smap; u64 cost, n_buckets; int err;
if (attr->map_flags & ~STACK_CREATE_FLAG_MASK) return ERR_PTR(-EINVAL);
/* check sanity of attributes */ if (attr->max_entries == 0 || attr->key_size != 4 || value_size < 8 || value_size % 8) return ERR_PTR(-EINVAL);
BUILD_BUG_ON(sizeof(struct bpf_stack_build_id) % sizeof(u64)); if (attr->map_flags & BPF_F_STACK_BUILD_ID) { if (value_size % sizeof(struct bpf_stack_build_id) || value_size / sizeof(struct bpf_stack_build_id) > sysctl_perf_event_max_stack) return ERR_PTR(-EINVAL); } else if (value_size / 8 > sysctl_perf_event_max_stack) return ERR_PTR(-EINVAL);
/* hash table size must be power of 2; roundup_pow_of_two() can overflow * into UB on 32-bit arches, so check that first */ if (attr->max_entries > 1UL << 31) return ERR_PTR(-E2BIG);
n_buckets = roundup_pow_of_two(attr->max_entries);
cost = n_buckets * sizeof(struct stack_map_bucket *) + sizeof(*smap); smap = bpf_map_area_alloc(cost, bpf_map_attr_numa_node(attr)); if (!smap) return ERR_PTR(-ENOMEM);
bpf_map_init_from_attr(&smap->map, attr); smap->n_buckets = n_buckets;
err = get_callchain_buffers(sysctl_perf_event_max_stack); if (err) goto free_smap;
err = prealloc_elems_and_freelist(smap); if (err) goto put_buffers;
return &smap->map;
put_buffers: put_callchain_buffers();free_smap: bpf_map_area_free(smap); return ERR_PTR(err);}
static int fetch_build_id(struct vm_area_struct *vma, unsigned char *build_id, bool may_fault){ return may_fault ? build_id_parse(vma, build_id, NULL) : build_id_parse_nofault(vma, build_id, NULL);}
static inline void stack_map_build_id_set_ip(struct bpf_stack_build_id *id){ id->status = BPF_STACK_BUILD_ID_IP; memset(id->build_id, 0, BUILD_ID_SIZE_MAX);}
static inline u64 stack_map_build_id_offset(unsigned long vm_pgoff, unsigned long vm_start, u64 ip){ return (vm_pgoff << PAGE_SHIFT) + ip - vm_start;}
static inline void stack_map_build_id_set_valid(struct bpf_stack_build_id *id, u64 offset, const unsigned char *build_id){ id->status = BPF_STACK_BUILD_ID_VALID; id->offset = offset; if (id->build_id != build_id) memcpy(id->build_id, build_id, BUILD_ID_SIZE_MAX);}
/* * A cached VMA lookup result. The range [vm_start, vm_end) is always set. * vm_pgoff, file, build_id are set only when the build ID was resolved. * Zero vm_end marks the slot empty. build_id aliases the id_offs[] entry. */struct stack_map_cached_vma { unsigned long vm_start; unsigned long vm_end; unsigned long vm_pgoff; struct file *file; /* pinned in the sleepable path; NULL otherwise */ const unsigned char *build_id;};
/* * Per stack_map_get_build_id_offset() call cache of the last VMA with a build ID * resolved and the last VMA with no usable build ID. Adjacent stack frames tend * to land in the same VMA or the same backing file, so caching the last result * of each kind lets us skip unnecessary VMA lookups and build ID parse calls. * Keeping the two slots independent means a build-ID-less VMA doesn't evict the * last resolved build ID. */struct stack_map_build_id_cache { struct stack_map_cached_vma resolved; struct stack_map_cached_vma unresolved;};
/* * Fill @id from a cached range covering @ip. On a hit this writes @id (resolved * range -> build ID + offset, unresolved range -> raw ip) and returns 0; on a * miss it leaves @id untouched and returns -ENOENT. */static int stack_map_build_id_set_from_cache(struct stack_map_build_id_cache *cache, struct bpf_stack_build_id *id, u64 ip){ unsigned long vm_start, vm_end, vm_pgoff; u64 offset;
vm_start = cache->resolved.vm_start; vm_end = cache->resolved.vm_end; if (vm_end && ip >= vm_start && ip < vm_end) { vm_pgoff = cache->resolved.vm_pgoff; offset = stack_map_build_id_offset(vm_pgoff, vm_start, ip); stack_map_build_id_set_valid(id, offset, cache->resolved.build_id); return 0; }
vm_start = cache->unresolved.vm_start; vm_end = cache->unresolved.vm_end; if (vm_end && ip >= vm_start && ip < vm_end) { stack_map_build_id_set_ip(id); return 0; }
return -ENOENT;}
/* * Record @vma's build ID as the last resolved one. @file is the pinned backing * file in the sleepable path (released when evicted), or NULL otherwise. */static void stack_map_build_id_cache_set_resolved(struct stack_map_build_id_cache *cache, struct file *file, const unsigned char *build_id, unsigned long vm_start, unsigned long vm_end, unsigned long vm_pgoff){ if (cache->resolved.file) fput(cache->resolved.file); cache->resolved = (struct stack_map_cached_vma){ .vm_start = vm_start, .vm_end = vm_end, .vm_pgoff = vm_pgoff, .file = file, .build_id = build_id, };}
/* Record [vm_start, vm_end) as a range with no usable build ID. */static void stack_map_build_id_cache_set_unresolved(struct stack_map_build_id_cache *cache, unsigned long vm_start, unsigned long vm_end){ cache->unresolved = (struct stack_map_cached_vma){ .vm_start = vm_start, .vm_end = vm_end, };}
struct stack_map_vma_lock { struct vm_area_struct *vma; struct mm_struct *mm;};
/* * Acquire a stable read-side reference on the VMA covering @ip. * * With CONFIG_PER_VMA_LOCK=y this returns a VMA with its per-VMA read * lock held and mmap_lock dropped, so the caller may sleep. * * With CONFIG_PER_VMA_LOCK=n it returns a VMA with mmap_lock still * held; the caller must snapshot any fields it needs and pin vm_file * with get_file() before stack_map_unlock_vma() drops mmap_lock, as * the VMA may be split, merged, or freed after that. * * Returns NULL on failure, in which case no lock is held. */static struct vm_area_struct *stack_map_lock_vma(struct stack_map_vma_lock *lock, unsigned long ip){ struct mm_struct *mm = lock->mm; struct vm_area_struct *vma;
/* noop under !CONFIG_PER_VMA_LOCK */ vma = lock_vma_under_rcu(mm, ip); if (vma) { lock->vma = vma; return vma; }
/* * Taking mmap_read_lock() is unsafe here, because the caller BPF * program might already hold it, causing a deadlock. */ if (!mmap_read_trylock(mm)) return NULL;
vma = vma_lookup(mm, ip); if (!vma) { mmap_read_unlock(mm); return NULL; }
#ifdef CONFIG_PER_VMA_LOCK if (!vma_start_read_locked(vma)) { mmap_read_unlock(mm); return NULL; } mmap_read_unlock(mm);#endif
lock->vma = vma; return vma;}
static void stack_map_unlock_vma(struct stack_map_vma_lock *lock){#ifdef CONFIG_PER_VMA_LOCK vma_end_read(lock->vma);#else mmap_read_unlock(lock->mm);#endif lock->vma = NULL;}
static void stack_map_get_build_id_offset_sleepable(struct bpf_stack_build_id *id_offs, u32 trace_nr){ struct stack_map_vma_lock lock = { .mm = current->mm }; struct stack_map_build_id_cache cache = {}; struct stack_map_cached_vma *res = &cache.resolved; unsigned long vm_pgoff, vm_start, vm_end; struct vm_area_struct *vma; struct file *file; u64 offset; u64 ip;
for (u32 i = 0; i < trace_nr; i++) { ip = READ_ONCE(id_offs[i].ip);
if (!stack_map_build_id_set_from_cache(&cache, &id_offs[i], ip)) continue;
vma = stack_map_lock_vma(&lock, ip); if (!vma) { stack_map_build_id_set_ip(&id_offs[i]); continue; }
vm_pgoff = vma->vm_pgoff; vm_start = vma->vm_start; vm_end = vma->vm_end;
if (vma_is_anonymous(vma) || !vma->vm_file) { stack_map_unlock_vma(&lock); stack_map_build_id_set_ip(&id_offs[i]); stack_map_build_id_cache_set_unresolved(&cache, vm_start, vm_end); continue; }
file = vma->vm_file; offset = stack_map_build_id_offset(vm_pgoff, vm_start, ip);
/* * Same backing file as the last resolved VMA (another mapping * of the same ELF binary): reuse its build_id without re-parsing. */ if (file == res->file) { stack_map_unlock_vma(&lock); stack_map_build_id_set_valid(&id_offs[i], offset, res->build_id); res->vm_start = vm_start; res->vm_end = vm_end; res->vm_pgoff = vm_pgoff; continue; }
file = get_file(file); stack_map_unlock_vma(&lock);
/* build_id_parse_file() may block on filesystem reads */ if (build_id_parse_file(file, id_offs[i].build_id, NULL)) { stack_map_build_id_set_ip(&id_offs[i]); fput(file); stack_map_build_id_cache_set_unresolved(&cache, vm_start, vm_end); continue; }
stack_map_build_id_set_valid(&id_offs[i], offset, id_offs[i].build_id); stack_map_build_id_cache_set_resolved(&cache, file, id_offs[i].build_id, vm_start, vm_end, vm_pgoff); }
if (res->file) fput(res->file);}
/* * Expects all id_offs[i].ip values to be set to correct initial IPs. * They will be subsequently: * - either adjusted in place to a file offset, if build ID fetching * succeeds; in this case id_offs[i].build_id is set to correct build ID, * and id_offs[i].status is set to BPF_STACK_BUILD_ID_VALID; * - or IP will be kept intact, if build ID fetching failed; in this case * id_offs[i].build_id is zeroed out and id_offs[i].status is set to * BPF_STACK_BUILD_ID_IP. */static void stack_map_get_build_id_offset(struct bpf_stack_build_id *id_offs, u32 trace_nr, bool user, bool may_fault){ struct mmap_unlock_irq_work *work = NULL; bool irq_work_busy = bpf_mmap_unlock_get_irq_work(&work); bool has_user_ctx = user && current && current->mm; struct stack_map_build_id_cache cache = {}; struct vm_area_struct *vma; int i;
if (may_fault && has_user_ctx) { stack_map_get_build_id_offset_sleepable(id_offs, trace_nr); return; }
/* If the irq_work is in use, fall back to report ips. Same * fallback is used for kernel stack (!user) on a stackmap with * build_id. */ if (!has_user_ctx || irq_work_busy || !mmap_read_trylock(current->mm)) { /* cannot access current->mm, fall back to ips */ for (i = 0; i < trace_nr; i++) stack_map_build_id_set_ip(&id_offs[i]); return; }
for (i = 0; i < trace_nr; i++) { u64 ip = READ_ONCE(id_offs[i].ip);
if (!stack_map_build_id_set_from_cache(&cache, &id_offs[i], ip)) continue;
vma = find_vma(current->mm, ip); if (!vma || vma_is_anonymous(vma) || fetch_build_id(vma, id_offs[i].build_id, may_fault)) { /* per entry fall back to ips; cache build-ID-less range */ stack_map_build_id_set_ip(&id_offs[i]); if (vma) stack_map_build_id_cache_set_unresolved(&cache, vma->vm_start, vma->vm_end); continue; } /* * mmap_lock is held for the whole loop, so the cached VMA * fields stay valid; no file pinning is needed here. */ stack_map_build_id_set_valid(&id_offs[i], stack_map_build_id_offset(vma->vm_pgoff, vma->vm_start, ip), id_offs[i].build_id); stack_map_build_id_cache_set_resolved(&cache, NULL, id_offs[i].build_id, vma->vm_start, vma->vm_end, vma->vm_pgoff); } bpf_mmap_unlock_mm(work, current->mm);}
static struct perf_callchain_entry *get_callchain_entry_for_task(struct task_struct *task, u32 max_depth){#ifdef CONFIG_STACKTRACE struct perf_callchain_entry *entry; int rctx;
entry = get_callchain_entry(&rctx);
if (!entry) return NULL;
entry->nr = stack_trace_save_tsk(task, (unsigned long *)entry->ip, max_depth, 0);
/* stack_trace_save_tsk() works on unsigned long array, while * perf_callchain_entry uses u64 array. For 32-bit systems, it is * necessary to fix this mismatch. */ if (__BITS_PER_LONG != 64) { unsigned long *from = (unsigned long *) entry->ip; u64 *to = entry->ip; int i;
/* copy data from the end to avoid using extra buffer */ for (i = entry->nr - 1; i >= 0; i--) to[i] = (u64)(from[i]); }
put_callchain_entry(rctx);
return entry;#else /* CONFIG_STACKTRACE */ return NULL;#endif}
static long __bpf_get_stackid(struct bpf_map *map, struct perf_callchain_entry *trace, u64 flags){ struct bpf_stack_map *smap = container_of(map, struct bpf_stack_map, map); struct stack_map_bucket *bucket, *new_bucket, *old_bucket; u32 hash, id, trace_nr, trace_len, i, max_depth; u32 skip = flags & BPF_F_SKIP_FIELD_MASK; bool user = flags & BPF_F_USER_STACK; u64 *ips; bool hash_matches;
if (trace->nr <= skip) /* skipping more than usable stack trace */ return -EFAULT;
max_depth = stack_map_calculate_max_depth(map->value_size, stack_map_data_size(map), flags); trace_nr = min_t(u32, trace->nr - skip, max_depth - skip); trace_len = trace_nr * sizeof(u64); ips = trace->ip + skip; hash = jhash2((u32 *)ips, trace_len / sizeof(u32), 0); id = hash & (smap->n_buckets - 1); bucket = READ_ONCE(smap->buckets[id]);
hash_matches = bucket && bucket->hash == hash; /* fast cmp */ if (hash_matches && flags & BPF_F_FAST_STACK_CMP) return id;
if (stack_map_use_build_id(map)) { struct bpf_stack_build_id *id_offs;
/* for build_id+offset, pop a bucket before slow cmp */ new_bucket = (struct stack_map_bucket *) pcpu_freelist_pop(&smap->freelist); if (unlikely(!new_bucket)) return -ENOMEM; new_bucket->nr = trace_nr; id_offs = (struct bpf_stack_build_id *)new_bucket->data; for (i = 0; i < trace_nr; i++) id_offs[i].ip = ips[i]; stack_map_get_build_id_offset(id_offs, trace_nr, user, false /* !may_fault */); trace_len = trace_nr * sizeof(struct bpf_stack_build_id); if (hash_matches && bucket->nr == trace_nr && memcmp(bucket->data, new_bucket->data, trace_len) == 0) { pcpu_freelist_push(&smap->freelist, &new_bucket->fnode); return id; } if (bucket && !(flags & BPF_F_REUSE_STACKID)) { pcpu_freelist_push(&smap->freelist, &new_bucket->fnode); return -EEXIST; } } else { if (hash_matches && bucket->nr == trace_nr && memcmp(bucket->data, ips, trace_len) == 0) return id; if (bucket && !(flags & BPF_F_REUSE_STACKID)) return -EEXIST;
new_bucket = (struct stack_map_bucket *) pcpu_freelist_pop(&smap->freelist); if (unlikely(!new_bucket)) return -ENOMEM; memcpy(new_bucket->data, ips, trace_len); }
new_bucket->hash = hash; new_bucket->nr = trace_nr;
old_bucket = xchg(&smap->buckets[id], new_bucket); if (old_bucket) pcpu_freelist_push(&smap->freelist, &old_bucket->fnode); return id;}
BPF_CALL_3(bpf_get_stackid, struct pt_regs *, regs, struct bpf_map *, map, u64, flags){ u32 elem_size = stack_map_data_size(map); bool user = flags & BPF_F_USER_STACK; struct perf_callchain_entry *trace; bool kernel = !user; u32 max_depth;
if (unlikely(flags & ~(BPF_F_SKIP_FIELD_MASK | BPF_F_USER_STACK | BPF_F_FAST_STACK_CMP | BPF_F_REUSE_STACKID))) return -EINVAL;
max_depth = stack_map_calculate_max_depth(map->value_size, elem_size, flags); trace = get_perf_callchain(regs, kernel, user, max_depth, false, false, 0);
if (unlikely(!trace)) /* couldn't fetch the stack trace */ return -EFAULT;
return __bpf_get_stackid(map, trace, flags);}
const struct bpf_func_proto bpf_get_stackid_proto = { .func = bpf_get_stackid, .gpl_only = true, .ret_type = RET_INTEGER, .arg1_type = ARG_PTR_TO_CTX, .arg2_type = ARG_CONST_MAP_PTR, .arg3_type = ARG_ANYTHING,};
static __u64 count_kernel_ip(struct perf_callchain_entry *trace){ __u64 nr_kernel = 0;
while (nr_kernel < trace->nr) { if (trace->ip[nr_kernel] == PERF_CONTEXT_USER) break; nr_kernel++; } return nr_kernel;}
BPF_CALL_3(bpf_get_stackid_pe, struct bpf_perf_event_data_kern *, ctx, struct bpf_map *, map, u64, flags){ struct perf_event *event = ctx->event; struct perf_callchain_entry *trace; bool kernel, user; __u64 nr_kernel; int ret;
/* perf_sample_data doesn't have callchain, use bpf_get_stackid */ if (!(event->attr.sample_type & PERF_SAMPLE_CALLCHAIN)) return bpf_get_stackid((unsigned long)(ctx->regs), (unsigned long) map, flags, 0, 0);
if (unlikely(flags & ~(BPF_F_SKIP_FIELD_MASK | BPF_F_USER_STACK | BPF_F_FAST_STACK_CMP | BPF_F_REUSE_STACKID))) return -EINVAL;
user = flags & BPF_F_USER_STACK; kernel = !user;
trace = ctx->data->callchain; if (unlikely(!trace)) return -EFAULT;
nr_kernel = count_kernel_ip(trace); __u64 nr = trace->nr; /* save original */
if (kernel) { trace->nr = nr_kernel; ret = __bpf_get_stackid(map, trace, flags); } else { /* user */ u64 skip = flags & BPF_F_SKIP_FIELD_MASK;
skip += nr_kernel; if (skip > BPF_F_SKIP_FIELD_MASK) return -EFAULT;
flags = (flags & ~BPF_F_SKIP_FIELD_MASK) | skip; ret = __bpf_get_stackid(map, trace, flags); }
/* restore nr */ trace->nr = nr;
return ret;}
const struct bpf_func_proto bpf_get_stackid_proto_pe = { .func = bpf_get_stackid_pe, .gpl_only = false, .ret_type = RET_INTEGER, .arg1_type = ARG_PTR_TO_CTX, .arg2_type = ARG_CONST_MAP_PTR, .arg3_type = ARG_ANYTHING,};
static long __bpf_get_stack(struct pt_regs *regs, struct task_struct *task, struct perf_callchain_entry *trace_in, void *buf, u32 size, u64 flags, bool may_fault){ u32 trace_nr, copy_len, elem_size, max_depth; bool user_build_id = flags & BPF_F_USER_BUILD_ID; bool crosstask = task && task != current; u32 skip = flags & BPF_F_SKIP_FIELD_MASK; bool user = flags & BPF_F_USER_STACK; struct perf_callchain_entry *trace; bool kernel = !user; int err = -EINVAL; u64 *ips;
if (unlikely(flags & ~(BPF_F_SKIP_FIELD_MASK | BPF_F_USER_STACK | BPF_F_USER_BUILD_ID))) goto clear; if (kernel && user_build_id) goto clear;
elem_size = user_build_id ? sizeof(struct bpf_stack_build_id) : sizeof(u64); if (unlikely(size % elem_size)) goto clear;
/* cannot get valid user stack for task without user_mode regs */ if (task && user && !user_mode(regs)) goto err_fault;
/* get_perf_callchain does not support crosstask user stack walking * but returns an empty stack instead of NULL. */ if (crosstask && user) { err = -EOPNOTSUPP; goto clear; }
max_depth = stack_map_calculate_max_depth(size, elem_size, flags);
if (may_fault) rcu_read_lock(); /* need RCU for perf's callchain below */
if (trace_in) { trace = trace_in; trace->nr = min_t(u32, trace->nr, max_depth); } else if (kernel && task) { trace = get_callchain_entry_for_task(task, max_depth); } else { trace = get_perf_callchain(regs, kernel, user, max_depth, crosstask, false, 0); }
if (unlikely(!trace) || trace->nr < skip) { if (may_fault) rcu_read_unlock(); goto err_fault; }
trace_nr = trace->nr - skip; copy_len = trace_nr * elem_size;
ips = trace->ip + skip; if (user_build_id) { struct bpf_stack_build_id *id_offs = buf; u32 i;
for (i = 0; i < trace_nr; i++) id_offs[i].ip = ips[i]; } else { memcpy(buf, ips, copy_len); }
/* trace/ips should not be dereferenced after this point */ if (may_fault) rcu_read_unlock();
if (user_build_id) stack_map_get_build_id_offset(buf, trace_nr, user, may_fault);
if (size > copy_len) memset(buf + copy_len, 0, size - copy_len); return copy_len;
err_fault: err = -EFAULT;clear: memset(buf, 0, size); return err;}
BPF_CALL_4(bpf_get_stack, struct pt_regs *, regs, void *, buf, u32, size, u64, flags){ return __bpf_get_stack(regs, NULL, NULL, buf, size, flags, false /* !may_fault */);}
const struct bpf_func_proto bpf_get_stack_proto = { .func = bpf_get_stack, .gpl_only = true, .ret_type = RET_INTEGER, .arg1_type = ARG_PTR_TO_CTX, .arg2_type = ARG_PTR_TO_UNINIT_MEM, .arg3_type = ARG_CONST_SIZE_OR_ZERO, .arg4_type = ARG_ANYTHING,};
BPF_CALL_4(bpf_get_stack_sleepable, struct pt_regs *, regs, void *, buf, u32, size, u64, flags){ return __bpf_get_stack(regs, NULL, NULL, buf, size, flags, true /* may_fault */);}
const struct bpf_func_proto bpf_get_stack_sleepable_proto = { .func = bpf_get_stack_sleepable, .gpl_only = true, .ret_type = RET_INTEGER, .arg1_type = ARG_PTR_TO_CTX, .arg2_type = ARG_PTR_TO_UNINIT_MEM, .arg3_type = ARG_CONST_SIZE_OR_ZERO, .arg4_type = ARG_ANYTHING,};
static long __bpf_get_task_stack(struct task_struct *task, void *buf, u32 size, u64 flags, bool may_fault){ struct pt_regs *regs; long res = -EINVAL;
if (!try_get_task_stack(task)) return -EFAULT;
regs = task_pt_regs(task); if (regs) res = __bpf_get_stack(regs, task, NULL, buf, size, flags, may_fault); put_task_stack(task);
return res;}
BPF_CALL_4(bpf_get_task_stack, struct task_struct *, task, void *, buf, u32, size, u64, flags){ return __bpf_get_task_stack(task, buf, size, flags, false /* !may_fault */);}
const struct bpf_func_proto bpf_get_task_stack_proto = { .func = bpf_get_task_stack, .gpl_only = false, .ret_type = RET_INTEGER, .arg1_type = ARG_PTR_TO_BTF_ID, .arg1_btf_id = &btf_tracing_ids[BTF_TRACING_TYPE_TASK], .arg2_type = ARG_PTR_TO_UNINIT_MEM, .arg3_type = ARG_CONST_SIZE_OR_ZERO, .arg4_type = ARG_ANYTHING,};
BPF_CALL_4(bpf_get_task_stack_sleepable, struct task_struct *, task, void *, buf, u32, size, u64, flags){ return __bpf_get_task_stack(task, buf, size, flags, true /* !may_fault */);}
const struct bpf_func_proto bpf_get_task_stack_sleepable_proto = { .func = bpf_get_task_stack_sleepable, .gpl_only = false, .ret_type = RET_INTEGER, .arg1_type = ARG_PTR_TO_BTF_ID, .arg1_btf_id = &btf_tracing_ids[BTF_TRACING_TYPE_TASK], .arg2_type = ARG_PTR_TO_UNINIT_MEM, .arg3_type = ARG_CONST_SIZE_OR_ZERO, .arg4_type = ARG_ANYTHING,};
BPF_CALL_4(bpf_get_stack_pe, struct bpf_perf_event_data_kern *, ctx, void *, buf, u32, size, u64, flags){ struct pt_regs *regs = (struct pt_regs *)(ctx->regs); struct perf_event *event = ctx->event; struct perf_callchain_entry *trace; bool kernel, user; int err = -EINVAL; __u64 nr_kernel;
if (!(event->attr.sample_type & PERF_SAMPLE_CALLCHAIN)) return __bpf_get_stack(regs, NULL, NULL, buf, size, flags, false /* !may_fault */);
if (unlikely(flags & ~(BPF_F_SKIP_FIELD_MASK | BPF_F_USER_STACK | BPF_F_USER_BUILD_ID))) goto clear;
user = flags & BPF_F_USER_STACK; kernel = !user;
err = -EFAULT; trace = ctx->data->callchain; if (unlikely(!trace)) goto clear;
nr_kernel = count_kernel_ip(trace);
if (kernel) { __u64 nr = trace->nr;
trace->nr = nr_kernel; err = __bpf_get_stack(regs, NULL, trace, buf, size, flags, false /* !may_fault */);
/* restore nr */ trace->nr = nr; } else { /* user */ u64 skip = flags & BPF_F_SKIP_FIELD_MASK;
skip += nr_kernel; if (skip > BPF_F_SKIP_FIELD_MASK) goto clear;
flags = (flags & ~BPF_F_SKIP_FIELD_MASK) | skip; err = __bpf_get_stack(regs, NULL, trace, buf, size, flags, false /* !may_fault */); } return err;
clear: memset(buf, 0, size); return err;
}
const struct bpf_func_proto bpf_get_stack_proto_pe = { .func = bpf_get_stack_pe, .gpl_only = true, .ret_type = RET_INTEGER, .arg1_type = ARG_PTR_TO_CTX, .arg2_type = ARG_PTR_TO_UNINIT_MEM, .arg3_type = ARG_CONST_SIZE_OR_ZERO, .arg4_type = ARG_ANYTHING,};
/* Called from eBPF program */static void *stack_map_lookup_elem(struct bpf_map *map, void *key){ return ERR_PTR(-EOPNOTSUPP);}
/* Called from syscall */static int stack_map_lookup_and_delete_elem(struct bpf_map *map, void *key, void *value, u64 flags){ return bpf_stackmap_extract(map, key, value, true);}
/* Called from syscall */int bpf_stackmap_extract(struct bpf_map *map, void *key, void *value, bool delete){ struct bpf_stack_map *smap = container_of(map, struct bpf_stack_map, map); struct stack_map_bucket *bucket, *old_bucket; u32 id = *(u32 *)key, trace_len;
if (unlikely(id >= smap->n_buckets)) return -ENOENT;
bucket = xchg(&smap->buckets[id], NULL); if (!bucket) return -ENOENT;
trace_len = bucket->nr * stack_map_data_size(map); memcpy(value, bucket->data, trace_len); memset(value + trace_len, 0, map->value_size - trace_len);
if (delete) old_bucket = bucket; else old_bucket = xchg(&smap->buckets[id], bucket); if (old_bucket) pcpu_freelist_push(&smap->freelist, &old_bucket->fnode); return 0;}
static int stack_map_get_next_key(struct bpf_map *map, void *key, void *next_key){ struct bpf_stack_map *smap = container_of(map, struct bpf_stack_map, map); u32 id;
WARN_ON_ONCE(!rcu_read_lock_held());
if (!key) { id = 0; } else { id = *(u32 *)key; if (id >= smap->n_buckets || !smap->buckets[id]) id = 0; else id++; }
while (id < smap->n_buckets && !smap->buckets[id]) id++;
if (id >= smap->n_buckets) return -ENOENT;
*(u32 *)next_key = id; return 0;}
static long stack_map_update_elem(struct bpf_map *map, void *key, void *value, u64 map_flags){ return -EINVAL;}
/* Called from syscall or from eBPF program */static long stack_map_delete_elem(struct bpf_map *map, void *key){ struct bpf_stack_map *smap = container_of(map, struct bpf_stack_map, map); struct stack_map_bucket *old_bucket; u32 id = *(u32 *)key;
if (unlikely(id >= smap->n_buckets)) return -E2BIG;
old_bucket = xchg(&smap->buckets[id], NULL); if (old_bucket) { pcpu_freelist_push(&smap->freelist, &old_bucket->fnode); return 0; } else { return -ENOENT; }}
/* Called when map->refcnt goes to zero, either from workqueue or from syscall */static void stack_map_free(struct bpf_map *map){ struct bpf_stack_map *smap = container_of(map, struct bpf_stack_map, map);
bpf_map_area_free(smap->elems); pcpu_freelist_destroy(&smap->freelist); bpf_map_area_free(smap); put_callchain_buffers();}
static u64 stack_map_mem_usage(const struct bpf_map *map){ struct bpf_stack_map *smap = container_of(map, struct bpf_stack_map, map); u64 value_size = map->value_size; u64 n_buckets = smap->n_buckets; u64 enties = map->max_entries; u64 usage = sizeof(*smap);
usage += n_buckets * sizeof(struct stack_map_bucket *); usage += enties * (sizeof(struct stack_map_bucket) + value_size); return usage;}
BTF_ID_LIST_SINGLE(stack_trace_map_btf_ids, struct, bpf_stack_map)const struct bpf_map_ops stack_trace_map_ops = { .map_meta_equal = bpf_map_meta_equal, .map_alloc = stack_map_alloc, .map_free = stack_map_free, .map_get_next_key = stack_map_get_next_key, .map_lookup_elem = stack_map_lookup_elem, .map_lookup_and_delete_elem = stack_map_lookup_and_delete_elem, .map_update_elem = stack_map_update_elem, .map_delete_elem = stack_map_delete_elem, .map_check_btf = map_check_no_btf, .map_mem_usage = stack_map_mem_usage, .map_btf_id = &stack_trace_map_btf_ids[0],};